A number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.
Endpoint Overrides
GOOGLE_CLOUD_CPP_VPC_ACCESS_SERVICE_ENDPOINT=... overrides the EndpointOption (which defaults to "vpcaccess.googleapis.com") used by MakeVpcAccessServiceConnection().
GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also set GOOGLE_CLOUD_CPP_ENABLE_CLOG to produce any output on the program's console.
See Also
google::cloud::TracingComponentsOptionGOOGLE_CLOUD_CPP_TRACING_OPTIONS=...: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.
See Also
google::cloud::GrpcTracingOptionsOptionGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes: turns on logging in the library, basically the library always "logs" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["\u003cp\u003eThis document provides a version history and environment variable configurations for the VPC Access C++ library, with the latest version being 2.37.0-rc.\u003c/p\u003e\n"],["\u003cp\u003eThe environment variable \u003ccode\u003eGOOGLE_CLOUD_CPP_VPC_ACCESS_SERVICE_ENDPOINT\u003c/code\u003e allows users to override the default endpoint used by \u003ccode\u003eMakeVpcAccessServiceConnection()\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eEnabling gRPC call tracing can be done by setting \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc\u003c/code\u003e, and setting \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG\u003c/code\u003e is recommended to see the output.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_CPP_TRACING_OPTIONS\u003c/code\u003e environment variable is used to modify gRPC tracing behaviors, such as the formatting and truncation of messages.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eGOOGLE_CLOUD_PROJECT\u003c/code\u003e environment variable is used in examples and tests to set the GCP project but does not affect the library itself.\u003c/p\u003e\n"]]],[],null,[]]
